Particle sizing in the abrasives industry is typically accomplished by passing abrasive particles through screens of different sizes resulting abrasive particles falling within an abrasives industry accepted specified nominal grade. Typical screening practices use vibration to speed up the screening process. While screening removes undesirably large and small particles, particles of varying shapes pass through the screen depending upon particle orientation. For example, a long narrow particle may be held up on a screen or may pass through the same screen depending on orientation. Thus, while abrasive particles are supplied according to particle size, the shape of the particles typically is not controlled.
Abrasive particles can be sorted by shape using various techniques (e.g., a vibratory shape sorting table) as is known in the abrasives industry. Such vibratory shape sorting tables are commonly used to remove extremes of the shape distribution within a lot of abrasive particles. These vibratory tables generally can be used to separate odd-shaped particles from a lot of abrasive grains of the same size range (e.g., ranging from nearly ideal crystals or cubo-octahedral shapes to broken particles having irregular shapes or high aspect ratio needle-like particles or platelets) using an inclined vibrating tray. Shape sorting is generally independent of particle size.
In abrasive grinding, the properties of the abrasives and their response to impact loading play a significant role in determining the results achievable. Commercially available abrasive particles are typically classified by size and optionally friability and/or crush strength. Within a particular size range, there is typically a range of particle shapes, generally ranging from lower aspect ratio to higher aspect ratio. However, with many high aspect ratio abrasive particle distributions, the platy/angular nature of the abrasive particles causes the particles to orient in irregular detrimental ways (e.g., laying down or oriented at odd angles) during incorporation into abrasive articles.
Many types of abrasive articles are known. Generally, abrasive articles include abrasive particles. The abrasive particles are usually retained in a binder matrix and optionally attached to a substrate such as, for example a backing or a metallic disc.